The Federal and Confederate armies in the War of Secession were organized in practically the same way. There were a few points of difference, and in active service the numbers and arrangement of military forces varied and were changed.

INFANTRY

Squad: any small number of men, usually 7, under command of a corporal.

Platoon: a subdivision, usually half, of a company under a lieutenant.

Company: from 83 to 125 men under a captain.

Battalion: 2 or more, usually four, companies under a major.

Regiment: 10 companies—or 3 battalions of 4 companies each—under a colonel or a lieutenant-colonel.

Brigade: 3 to 5 regiments under a brigadier-general.

Division: 2 to 5 brigades under a major-general.

Army corps: 2 or more divisions under a major-general or a lieutenant-general,—organized as a complete army and sufficient in itself for all the operations of war.

CAVALRY

Squad: any small number of men, usual 7, under a corporal.

Platoon: a sub-division, usually half, of a company under a lieutenant.

Troop: 2 to 6 platoons, 76 to 100 men, under a captain.

Squadron: 2 to 4 troops under a senior captain or a major.

Regiment: 10 troops—or 4 to 6 squadrons—under a colonel.

Brigade: 3 or 4 regiments under a brigadier-general.

Division: 2 to 4 brigades under a major-general.

ARTILLERY

Battery: usually 144 men with 4 guns and 2 howitzers, under a captain.

Battalion: 3 to 4 batteries under a major.

Regiment: 2 to 8 battalions under a colonel.

When infantry regiments are combined into brigades, brigades into divisions, and divisions into army corps,—cavalry, artillery, and certain other auxiliary troops, such as engineers, signal corps, etc., are joined with them in such proportions as are necessary. Every unit, from the company up, has its own supply and ammunition wagons, field hospitals, etc.